The dual argument holds well when cockpit space is limited !!
Just purchased one of the 178m 's for the club RIB at 159 quid!
The colour one was tempting, but at £250 extra for the same animal with a colour screen, we can live with B/W
It replaces our old Garmin FFB 100 (well pleased with that we was)and Furuno GPS that got toasted last year!!
The dual frequency sounder included gives an excellent bottom picture and as divers, the fish finder confirms the presence of a wreck with life congregating around the viewed plot,,
Although the B/W version is discontinued, it still has the 1 year warranty and support and IMHO is excellent VFM....